On fast machines, it's possible for applications such as pgbench
to issue connection requests so quickly that the postmaster's
listen queue overflows in the kernel, resulting in unexpected
failures (with not-very-helpful error messages). Most modern OSes
allow the queue size to be increased, so document how to do that.
Per report from Kevin McKibbin.
Discussion: https://postgr.es/m/CADc_NKg2d+oZY9mg4DdQdoUcGzN2kOYXBu-3--RW_hEe0tUV=g@mail.gmail.com
sysctl is more portable than Linux's /proc/sys file tree, and
often easier to use too. That's why most of our docs refer to
sysctl when talking about how to adjust kernel parameters.
Bring the few stragglers into line.
Discussion: https://postgr.es/m/361175.1661187463@sss.pgh.pa.us
Previously, if an extension script did CREATE OR REPLACE and there was
an existing object not belonging to the extension, it would overwrite
the object and adopt it into the extension. This is problematic, first
because the overwrite is probably unintentional, and second because we
didn't change the object's ownership. Thus a hostile user could create
an object in advance of an expected CREATE EXTENSION command, and would
then have ownership rights on an extension object, which could be
modified for trojan-horse-type attacks.
Hence, forbid CREATE OR REPLACE of an existing object unless it already
belongs to the extension. (Note that we've always forbidden replacing
an object that belongs to some other extension; only the behavior for
previously-free-standing objects changes here.)
For the same reason, also fail CREATE IF NOT EXISTS when there is
an existing object that doesn't belong to the extension.
Our thanks to Sven Klemm for reporting this problem.
Security: CVE-2022-2625
This is a backpatch to branches 10-14 of the following commits:
7170f2159f Allow "in place" tablespaces.
c6f2f01611 Fix pg_basebackup with in-place tablespaces.
f6f0db4d62 Fix pg_tablespace_location() with in-place tablespaces
7a7cd84893 doc: Remove mention to in-place tablespaces for pg_tablespace_location()
5344723755 Remove unnecessary Windows-specific basebackup code.
In-place tablespaces were introduced as a testing helper mechanism, but
they are going to be used for a bugfix in WAL replay to be backpatched
to all stable branches.
I (Álvaro) had to adjust some code to account for lack of
get_dirent_type() in branches prior to 14.
Author: Thomas Munro <thomas.munro@gmail.com>
Author: Michaël Paquier <michael@paquier.xyz>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/20220722081858.omhn2in5zt3g4nek@alvherre.pgsql
We have a few commands that "can't run in a transaction block",
meaning that if they complete their processing but then we fail
to COMMIT, we'll be left with inconsistent on-disk state.
However, the existing defenses for this are only watertight for
simple query protocol. In extended protocol, we didn't commit
until receiving a Sync message. Since the client is allowed to
issue another command instead of Sync, we're in trouble if that
command fails or is an explicit ROLLBACK. In any case, sitting
in an inconsistent state while waiting for a client message
that might not come seems pretty risky.
This case wasn't reachable via libpq before we introduced pipeline
mode, but it's always been an intended aspect of extended query
protocol, and likely there are other clients that could reach it
before.
To fix, set a flag in PreventInTransactionBlock that tells
exec_execute_message to force an immediate commit. This seems
to be the approach that does least damage to existing working
cases while still preventing the undesirable outcomes.
While here, add some documentation to protocol.sgml that explicitly
says how to use pipelining. That's latent in the existing docs if
you know what to look for, but it's better to spell it out; and it
provides a place to document this new behavior.
Per bug #17434 from Yugo Nagata. It's been wrong for ages,
so back-patch to all supported branches.
Discussion: https://postgr.es/m/17434-d9f7a064ce2a88a3@postgresql.org
We didn't explicitly say that random() uses a randomly-chosen seed
if you haven't called setseed(). Do so.
Also, remove ref/set.sgml's no-longer-accurate (and never very
relevant) statement that the seed value is multiplied by 2^31-1.
Back-patch to v12 where set.sgml's claim stopped being true.
The claim that we use a source of random bits as seed was debatable
before 4203842a1, too, so v12 seems like a good place to stop.
Per question from Carl Sopchak.
Discussion: https://postgr.es/m/f37bb937-9d99-08f0-4de7-80c91a3cfc2e@sopchak.me
SPI_commit previously left it up to the caller to recover from any error
occurring during commit. Since that's complicated and requires use of
low-level xact.c facilities, it's not too surprising that no caller got
it right. Let's move the responsibility for cleanup into spi.c. Doing
that requires redefining SPI_commit as starting a new transaction, so
that it becomes equivalent to SPI_commit_and_chain except that you get
default transaction characteristics instead of preserving the prior
transaction's characteristics. We can make this pretty transparent
API-wise by redefining SPI_start_transaction() as a no-op. Callers
that expect to do something in between might be surprised, but
available evidence is that no callers do so.
Having made that API redefinition, we can fix this mess by having
SPI_commit[_and_chain] trap errors and start a new, clean transaction
before re-throwing the error. Likewise for SPI_rollback[_and_chain].
Some cleanup is also needed in AtEOXact_SPI, which was nowhere near
smart enough to deal with SPI contexts nested inside a committing
context.
While plperl and pltcl need no changes beyond removing their now-useless
SPI_start_transaction() calls, plpython needs some more work because it
hadn't gotten the memo about catching commit/rollback errors in the
first place. Such an error resulted in longjmp'ing out of the Python
interpreter, which leaks Python stack entries at present and is reported
to crash Python 3.11 altogether. Add the missing logic to catch such
errors and convert them into Python exceptions.
This is a back-patch of commit 2e517818f. That's now aged long enough
to reduce the concerns about whether it will break something, and we
do need to ensure that supported branches will work with Python 3.11.
Peter Eisentraut and Tom Lane
Discussion: https://postgr.es/m/3375ffd8-d71c-2565-e348-a597d6e739e3@enterprisedb.com
Discussion: https://postgr.es/m/17416-ed8fe5d7213d6c25@postgresql.org
The previous wording was "the underlying data type's default collation
is used", which is wrong or at least misleading. The domain inherits
the base type's collation behavior, which if "default" actually can
mean that we use some non-default collation obtained from elsewhere.
Per complaint from Jian He.
Discussion: https://postgr.es/m/CACJufxHMR8_4WooDPjjvEdaxB2hQ5a49qthci8fpKP0MKemVRQ@mail.gmail.com
This reverts commits a04ccf6df et al. in the back branches only.
There was some disagreement already over whether to back-patch
157f8739a, on the grounds that it is the sort of behavioral
change that we don't like to back-patch. Furthermore, it now
looks like the logic needs some more work, which we don't have
time for before the upcoming 14.4 release. Revert for now, and
perhaps reconsider later.
Discussion: https://postgr.es/m/17504-76b68018e130415e@postgresql.org
The patch introducing jsonpath dropped a para about that between
two related examples, and didn't bother updating the introductory
sentences that it falsified. The grammar was pretty shaky as well.
psql --single-transaction is able to handle multiple -c and -f switches
in a single transaction since d5563d7d, but this had the surprising
behavior of forcing a transaction COMMIT even if psql failed with an
error in the client (for example incorrect path given to \copy), which
would generate an error, but still commit any changes that were already
applied in the backend. This commit makes the behavior more consistent,
by enforcing a transaction ROLLBACK if any commands fail, both
client-side and backend-side, so as no changes are applied if one error
happens in any of them.
Some tests are added on HEAD to provide some coverage about all that.
Backend-side errors are unreliable as IPC::Run can complain on SIGPIPE
if psql quits before reading a query result, but that should work
properly in the case where any errors come from psql itself, which is
what the original report is about.
Reported-by: Christoph Berg
Author: Kyotaro Horiguchi, Michael Paquier
Discussion: https://postgr.es/m/17504-76b68018e130415e@postgresql.org
Backpatch-through: 10
The previous entry invited confusion between what uniq() does
by itself and what it does when combined with sort(). The latter
usage is pretty useful so we should show it, but add an additional
example to clarify the results of uniq() alone.
Per suggestion from Martin Kalcher. Back-patch to v13, where
we switched to formatting that supports multiple examples.
Discussion: https://postgr.es/m/165407884456.573551.8779012279828726162@wrigleys.postgresql.org
The PostgreSQL limitations section of the documents mentioned the limit
on the number of columns that can exist in a table. Users might be
surprised to find that there's also a limit on the number of columns that
can exist in a targetlist. Users may experience restrictions which
surprise them if they happened to select a large number of columns from
several tables with many columns. Here we document that there is a
limitation on this and mention what that limit actually is.
Wording proposal by Alvaro Herrera
Reported-by: Vladimir Sitnikov
Author: Dave Crammer
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/CAB=Je-E18aTYpNqje4mT0iEADpeGLSzwUvo3H9kRRuDdsNo4aQ@mail.gmail.com
Backpatch-through: 12, where the limitations section was added
Bruce Momjian
Tom Lane
Tatsuo Ishii
Alvaro Herrera
Michael Paquier
Etsuro Fujita
David Rowley